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Author Topic: APS-PBG-650/750 build/change  (Read 10702 times)
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Koncretekid
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« Reply #45 on: February 12, 2014, 06:51:12 PM »

Jim,
A stupid question for you. Did you re-establish top dead center on each cylinder before you degreed the cam for the second cylinder (rather than assume that it would be 80 degrees later)?
Tom
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We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!
JimL
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« Reply #46 on: February 12, 2014, 09:42:12 PM »

Yes, I did.  I bought one of those kits with the stoppers that thread into the plug holes.  That sure makes it easy.

Anyway, I did every cam lobe twice, resetting my equipment each time to be sure my results would duplicate.  Today I ran the cam I used in 2010 for the first 750 record and found similar problems.

Vinsky, do those Vincents have a similar design?
JimL
« Last Edit: February 12, 2014, 09:44:54 PM by JimL » Logged
edinlr
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« Reply #47 on: February 12, 2014, 10:26:07 PM »

Jim,

The Vincent did use followers, but the pushrod is just above the cam, not offset like the CX.  I would think that they would still have to mirror the ramps the same as the CX if the cams were not cut the same way on each side.  Up top, the motion takes a 90 degree turn to open the valves.  Another interesting thing is they use two guides, one below and one above the rocker.  In the 50's the engine was described as a semi-overhead cam.
« Last Edit: February 12, 2014, 10:29:11 PM by edinlr » Logged

Honda CX650 turbo
JimL
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« Reply #48 on: February 12, 2014, 11:56:49 PM »

I checked rocker ratio with my Sig Erson wheel, based on lift at the valve and the cam.  Our rocker ratio is basically 1:1.  The Vincent looks like it is a little higher, I think.

Our problem is a slight shift in rocker ratio as the cam sweeps the follower pad.  My next step is to put Prussian Blue on the follower pads and check sweep range on each rocker, with all the current grinds, to find out if we can get to the duration numbers I am targeting.

The "bumps" in the lift and close ramps graphing lines are caused by a squaring effect meeting the slightly curved pads on the followers.  As we extend duration, that squaring effect will increase.  That might be why the Ilmor pushrod Indy engine ran roller followers (along with durability for the time at high rpm). 

Yep...I think knitting needles would be cheaper, but my old mechanics hands are so scarred up I'd get tangled in the yarn.
JimL
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Vinsky
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« Reply #49 on: February 13, 2014, 02:18:10 AM »

Maybe you can see how symmetrical the lobes are and how easy they could be ground basakward.


* lifter.jpg (182.74 KB, 1200x900 - viewed 224 times.)
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John
JimL
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« Reply #50 on: February 13, 2014, 11:23:02 AM »

 Yes, they are similar to my original camshafts it appears.

Thanks, JimL
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JimL
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« Reply #51 on: December 29, 2014, 08:33:42 PM »

Many changes, including some different cam designs over the last year.  Bike only wound up 10" longer and it looks like things are starting to fit.


This is a dummy engine.  I have many bad blocks and heads, these days, useful for mocking stuff up.

JimL


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« Last Edit: December 29, 2014, 08:35:35 PM by JimL » Logged
JimL
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« Reply #52 on: December 30, 2014, 01:24:55 AM »

Short note about the pics above.....guess I didnt explain much. embarassed

I had some good advice from a friend who uses these type blowers making 500 hp from 240 inch engines, on the street, on pump gas.  He told me, "It is not possible to make the blower mount too strong, or too heavy."  There will be a strong bracket arrangement for the rear, also (Shown temporarily bolted during fabrication).

Thats the reason for the 1/4" cold rolled steel plate, doubled, with back bracing.  Any oscillation of the blower itself will loosen every bolt or shear brackets.  This will use a Gates automatic tensioner and a "draw roller" to straighten the belt web coming off the blower pulley.  This method slightly shortens belt life, but allows longer periods of highest boost operation.

The window in the mount plate is for the forward exhaust header.  That took a while to cut on my converted vertical woodworking bandsaw (jackshafts and pulleys to get down to 43 RPM for 14" wheel).  Slow cutting, but gives a man time to think.

JimL
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JimL
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« Reply #53 on: January 13, 2015, 10:44:55 PM »

I decided I needed an outboard bearing to support the drive belt tension.  This is a "deep groove" Fafnir spindle bearing designed for a large mill, and good to 14,000 rpm+.  The aluminum block is as big as I could safely swing in my lathe.  I was able to get runout at the end of the crankshaft extension down to .001" before I installed the bearing support.  The crank spins easily with the belt tensioned to the blower.  The outboard carrier is mounted only to the engine, not to the motorcycle frame.  I can never get the engine positioned well enough in the stud holes to be certain of assembly repeatability.

That outboard bearing can be replaced without removing the carrier by simply pulling the crankshaft bolt.  I plan to bring spares and change often (along with belts).

The tensioner is for a GM product and belt tension is 85 lbs at this position.  The mount plate for the tensioner has a "spring" bolt to adjust belt guide at the tensioner pulley.  I was able to spin the crankshaft up to a little over 1000 rpm to get the alignment correct on this pulley.  Spinning a single throw crank in an empty block is a pretty wild experience.  The table shakes so bad that I had to climb on with the bike in order to get an Allen wrench into that "spring" bolt!  A lot of tools wound up on the floor.

The belt cover in the second photo also serves as an outboard stiffener to the forward edge of the blower mount plate.

A lot of rework going into the frame, while all this is going on....looks like a mess, right now, but bear with me folks.  It'll get better when welds get finished, corner braces get added, and Hammerite paint goes on!

JimL


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« Last Edit: January 13, 2015, 10:53:25 PM by JimL » Logged
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